There has been commercialized a multiple pane. In the multiple pane, a pair of glass panels are arranged facing each other, and a plurality of spacers are interposed between the pair of glass panels, and the pair of glass panels are bonded with a hermetic bond at peripheries thereof, and thus an inside space is defined by the pair of glass panels and the hermetic bond. The air in the inside space is exhausted to reduce the pressure of the inside space.
Such a multiple pane in which the pressure of the inside space is reduced has an air layer with a pressure lower than the atmospheric pressure between the pair of glass panels, and thus it is expected to show a greater heat insulating effect, a greater condensation-prevention effect, a greater sound-dampening effect that are greater than those of a multiple pane in which two glass panels are simply stacked. In recent years, the importance of saving energy has increased, and therefore the multiple pane including the space whose pressure is reduced has attracted a great attention as one type of eco-glass. The depressurized multiple pane is manufactured by: applying a sealant (e.g., low melting glass frit) onto the peripheries of the pair of glass panels separated at a predetermined distance by a plurality of spacers such as metal and ceramics; heating the sealant to hermetically bond the peripheries and thus form a space; and thereafter exhausting air in the inside space via an exhaust pipe made of glass or metal.
For example, Patent document 1 (JP 5-501896 A) and Patent document 2 (JP 11-324059 A) disclose the above-mentioned background arts.